Optimization of Correction Factor for Linearization with Tc-99m HM PAO and Tc-99m ECD Brain SPECT

We conducted this study to find the optimal correction factor() of Lassen's linearization algorithm which has been applied for correction of flow-limited uptake at a high flow range in d,l-hexamethylpropy leneamine oxime(HMPAO) and ethyl cysteinate dimer(ECD). Ten patients with chronic cerebral infarction were involved in this study. We obtained the corrected HMPAO and -ECD brain SPECT(single photon emission computed tomography) using the algorithm with values that varied from 0.1 to 10 and compared the results with regional cerebral blood flow determined by positron emission tomography (PET-rCBF). The multi-modal volume registration by maximization of mutual information was used for matching between PET-rCBF and SPECT images. The highest correlation coefficient between -HMPAO and -ECD brain uptake and PET-rCBF was revealed at 1.4 and 2.1, respectively. We concluded that the values of Lassen's linearization algorithm for -HMPAO and -ECD brain SPECT images were 1.4 and 2.1, respectively to indicate cerebral blood flow with comparison of PET-rCBF.